Python | Get the numeric prefix of given string

Given a string. the task is to print numeric prefix in string (if it is present in string). Given below are few methods to solve the task.

Method #1: Using Naive Method

# Python code to demonstrate 
# to get numeric prefix in string 
# if present 
  
# initialising string 
ini_string = "123abcjw"
ini_string2 = "abceddfgh"
  
# printing string and its length 
print ("initial string : ", ini_string, ini_string2) 
  
# code to find numeric prefix in string 
res1 = ''.join(c for c in ini_string if c in '0123456789') 
res2 = ''.join(c for c in ini_string2 if c in '0123456789') 
  
  
# printing resultant string 
print ("first string result: ", str(res1)) 
print ("second string result: ", str(res2)) 

Output:

initial string :  123abcjw abceddfgh
first string result:  123
second string result:

Method #2: Using takewhile

# Python code to demonstrate 
# to get numeric prefix in string 
# if present 
from itertools import takewhile 
  
# initialising string 
ini_string = "123abcjw"
ini_string2 = "abceddfgh"
  
# printing string and its length 
print ("initial string : ", ini_string, ini_string2) 
  
# code to find numeric prefix in string 
res1 = ''.join(takewhile(str.isdigit, ini_string)) 
res2 = ''.join(takewhile(str.isdigit, ini_string2)) 
  
# printing resultant string 
print ("first string result: ", res1) 
print ("second string result: ", res2) 

Output:

initial string :  123abcjw abceddfgh
first string result:  123
second string result:

Method #3: Using re.sub

# Python code to demonstrate 
# to get numeric prefix in string 
# if present 
import re 
  
# initialising string 
ini_string = "123abcjw"
ini_string2 = "abceddfgh"
  
# printing string and its length 
print ("initial string : ", ini_string, ini_string2) 
  
# code to find numeric prefix in string 
res1 = re.sub('\D.*', '', ini_string) 
res2 = re.sub('\D.*', '', ini_string2) 
  
  
# printing resultant string 
print ("first string result: ", str(res1)) 
print ("second string result: ", str(res2)) 

Output:

initial string :  123abcjw abceddfgh
first string result:  123
second string result:

Using Method #4: Using re.findall

# Python code to demonstrate 
# to get numeric prefix in string 
# if present 
import re 
  
# initialising string 
ini_string = "123abcjw"
ini_string2 = "abceddfgh"
  
# printing string and its length 
print ("initial string : ", ini_string, ini_string2) 
  
# code to find numeric prefix in string 
res1 = ''.join(re.findall('\d+', ini_string)) 
res2 = ''.join(re.findall('\d+', ini_string2)) 
  
# printing resultant string 
print ("first string result: ", str(res1)) 
print ("second string result: ", str(res2)) 

Output:

initial string :  123abcjw abceddfgh
first string result:  123
second string result:

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